Deleting data from magnetic disk media and random-access memory may be accomplished by various methods, such as an erase operation where the memory data is overwritten with other data, a delete operation, or by removing power from the device. However, storing data indefinitely in magnetic disk media or random-access memory results in an aging effect which causes traces or remnants of data to remain even after a deletion or erasure operation or after power to the memory is shut off.
This aging effect, known as data imprinting, defeats the ability to completely erase information stored in a memory. The data traces or remnants may provide sufficient information to enable the recovery of data. The longer the information is stored in a memory cell, the greater the possibility that the data will be preserved by imprinting and subsequently detectable even after erasure or deletion. Data imprinting may pose special data storage problems for security or other applications where the complete or guaranteed destruction of sensitive data is highly desirable.